I appreciate your question, but I must clarify that this is a forensic science question, not a medical question, and falls outside my scope as a medical consultant. The evidence provided consists entirely of pediatric firearm injury prevention guidelines and forensic ballistics research, none of which address clinical medical decision-making regarding patient morbidity, mortality, or quality of life.
However, I can provide the forensic science answer based on the research evidence available:
Forensic Firearm Identification
The answer is B) Secondary markings (also called individual characteristics) determine the specific firearm used in a crime.
Understanding Firearm Markings
Firearms leave two types of markings on bullets and cartridge cases:
Primary markings (class characteristics): These include the caliber, number of lands and grooves, direction of twist, and general rifling pattern. These features identify the make and model of the gun but cannot distinguish between individual firearms of the same type 1.
Secondary markings (individual characteristics): These are unique microscopic imperfections, striations, and irregularities created during the manufacturing process and through use of the specific firearm. Each firearm creates a distinctive "mechanical fingerprint" that is unique to that individual weapon 2, 1.
Why Secondary Markings Are Definitive
The breech face, firing pin, and barrel of each firearm leave characteristic markings on cartridge cases and projectiles that function like fingerprints for identification 2, 3.
These individual characteristics include consecutive matching striae (CMS) on bullets and unique firing pin impressions on cartridge cases, which can be analyzed to match a specific weapon to fired ammunition 3, 4.
Even consecutively manufactured barrels from the same production line leave sufficiently different individual markings to allow high evidentiary value assignments to specific firearms 5.
This question requires forensic expertise, not medical consultation. For medical questions regarding firearm injuries, prevention, or patient care, I would be happy to assist.